This invention relates to a chuck for fixing a rotary tool such as a drill and an end mill to a machine tool.
An ordinary chuck is equipped with a taper shank for fitting the chuck to a spindle of a machine tool at one of the ends thereof in its axial direction and a tool support for fitting a rotary tool at the other end. In addition, the chuck includes a fastening ring for regulating fastening force by the tool support and fitted over the tool support.
When the rotary tool is fitted to, or removed from, the chuck while the conventional chuck is in use, braking force is first applied to a driving device such as a gear mechanism and a motor for driving a spindle of the machine tool so as to fix the spindle. The fastening ring of the chuck is then rotated by a tool such as a spanner under this state to regulate the fastening force of the tool support, and the rotary tool is changed thereafter.
To tightly fasten the rotary tool to the chuck, the fastening ring must be fastened beforehand by a considerably great force. This fastening ring receives rotating torque of the motor during machining and is fastened further tightly.
To fit and remove the rotary tool to and from the chuck, therefore, a brake device is necessary for fixing the spindle of the machine tool, and moreover, the operation of this brake device and turning of the fastening ring are necessary.
Since a great force is required for turning this fastening ring, it is not so easy to fit the rotary tool to the chuck, and it is more difficult to remove the rotary tool from the chuck.